1. Field of the Invention
This invention relates to a system for authenticating transmitted video signals by selecting portions of the video signal and generating authentication codes that are transmitted with those portions for verification at a receiving location.
2. Description of the Related Art
Transmission of video signals is widely used for a variety of purposes. In some circumstances, the channels of communication are tightly controlled and it is reasonable to conclude that a received signal is exactly consistent with a transmitted signal. In many, if not most, circumstances, however, the communication channels are not tightly controlled. Therefore, it is necessary for two parties who are communicating with each other to authenticate received signals to ensure that the received signal is from an expected source and has not been tampered with in transit. Ideally, an authentication strategy verifies that a received signal is from the appropriate source (i.e., authenticity) and that the content is what was sent by the transmitter (i.e., signal integrity).
A variety of strategies have been proposed for authenticating signals in transit. Encryption algorithms have been utilized in a variety of fields including remote keyless entry systems and video systems. One example of a video system authentication strategy is shown in U.S. Pat. No. 5,499,294. In that arrangement a digital camera processor includes a private key that is embedded into the processor. Digital cameras having a public key that corresponds to the private key are able to receive information from the processor and to determine, using a known strategy, whether the received signal is from the appropriate source.
One limitation on currently proposed systems is that they are not capable of efficiently handling large amounts of video data. Another limitation is that many proposals do not provide a secure enough system that is effectively tamper proof. There is a need for a system that handles large amounts of video data in an efficient manner and provides results that are sufficiently secure. This invention addresses that need by providing a unique approach to authenticating video signals that are transmitted from one location to another.
This invention is useful for authenticating a video signal that is transmitted from one location to a second location. A system designed according to this invention identifies portions of a video signal and provides an authentication code for each portion that is then used for authentication purposes at a receiving location.
A system for ensuring the authenticity of data within a video signal that is transmitted from a first location to a second location, which is designed according to this invention, includes several components. A selector module selects at least one portion of the video signal. An authentication code generating module appends a key to the selected portion and then generates an authentication code using the appended portion. A transmitter portion appends the authentication code to the selected portion of the video signal and transmits the appended portion, including the authentication code, from the first location.
In the most preferred embodiment, the selector module identifies portions of the video signal by locating synchronizing codes in the video signal and choosing the data between adjacent synchronizing codes as each selected portion. Preferably an entire video signal is processed so that a plurality of portions between adjacent synchronizing codes each have a unique authentication code associated with them when the video signal is transmitted from the first location to the second location. At the second location, a second selector module identifies each portion of the transmitted signal. A deciphering module appends the key, which is the same as the key used at the first location, to the selected portion and then generates a second authentication code using the appended portion. An authentication module then authenticates the video signal at the second location by determining whether the second authentication code matches the authentication code that was sent along with the transmitted video signal portion.
A method associated with this invention includes several basic steps. First, a portion of a video signal is selected. Preferably, portions of the video signal are selected as the data between synchronizing codes associated with the video signal. A key is appended to at least one of the selected portions. An authentication code is generated using the appended selected portion. The authentication code is then appended to the selected portion and both are transmitted from the first location to the second location. At the second location a received signal portion is utilized to generate an associated second authentication code using the same key as used at the first location. The second authentication code is compared with the authentication code received from the first location to verify the authenticity of the transmitted signal.
A computer-readable medium including a plurality of computer-executable instructions for ensuring the authenticity of a video signal, which is transmitted from a first location to a second location, that is designed according to this invention includes several basic instructions. A first instruction directs a computer to select a portion of the video signal. A second instruction directs the computer to append a key to the selected portion. A third instruction directs the computer to generate an authentication code using the appended selected portion. A fourth instruction directs the computer to append the authentication code to the selected portion of the video signal so that both can be transmitted from the first location to the second location.